Euphorbiaceae

L In East Africa, the bark of this tree is reported to be used as a cathartic (Githens, 1949).

C The testa, constituting 40% of the weight of the kernels, possess no molluscicidal activity. Only alcoholic and aqueous extracts of the kernel were biologically active; chromatographic screening showed that the seeds contain alkaloids, amino acids and sterols as well as triterpenes or their saponins. Biological testing indicated that the zone corresponding to the sterols and triterpenes was the only active one. Finally, the molluscicidal action was found to be due to at least two saponins and the activity was greatly increased by freeing the saponins from the other constituents of the seeds. Activity was raised from 2 p.p.m. for the alcoholic extract to 0.06 p.p.m. for the purified saponins (El-Kheir and Salih, 1979).

P The crude ground seeds of this tree showed high molluscicidal activity compared to plants previously investigated (Amin et al., 1972).

Polygonum senegalense Meisn. syn. (P. glabrum of F.T.A.) POLYGONACEAE Polygonum senegalense forma albotomentosum R. Grah.

L These plants and related species are 'pounded with native natron and rubbed into the limbs as a remedy for rheumatic and other swellings, and applied to syphilitic sores' (Dalziel, 1937).

C The flavonoids luteolin, quercitin, luteolin-7-O-glucoside and quercitin-3-O-galac-toside have been isolated and identified in P. senegalense (Abd El-Gawad and El Zait, 1981). As aqueous extracts of the plants release cyanate ions on alkaline hydrolysis, the molluscicidal compounds may be chemically related to pseudo-cyanogenic glycosides or azoxyglycosides such as cycasin and macrozamin (Dossaji et al., 1977). In 1978, Maradufu and Ouma considered 2,4-dihydroxy-3,6-dimethoxy-chalcone to be responsible for the molluscicidal activity.

P Cut leaves of both above-mentioned varieties proved to be potent molluscicides. Tests were carried out with aqueous extracts of P. senegalense forma senegalense on the snails Biomphalaria pfeifferi and Lymnaea natalensis. Isolation of the highly water-soluble active principle increased the molluscicidal effects to 70% and 60% mortality after 1 h for Biomphalaria and Lymnaea, respectively, with concentrations of 25 p.p.m. and 100% mortality for both species after 24 h. The activce constituent was subsequently identified as quercetin-3(2'' )-galloylglycoside (Dossaji and Kubo, 1980). The fact that the plant grows near rivers, lakes, etc. should facilitate its use in the control of snails (Dossaji et al., 1977).

Jatropha gossypiifolia L. EUPHORBIACEAE

Wild cassada, red fig-nut flower Jatropha curcas L. Barbados nut

L The viscid sap is used to cure sores on the tongues of babies (Pthrush) (Irvine, 1961) and in India the leaves of J. gossypiifolia are applied to boils and carbuncles, eczema and rashes (Chopra et al., 1956). The rootbark of J. curcas, dried and pulverized, is applied as a dressing for sores (Irvine, 1930). The seeds are a (dangerous) purgative and are given as a remedy against venereal diseases (Dalziel, 1937).

C J. curcas contains a non-drying fixed oil consisting mainly of glycerides of stearic, palmitic, myristic, oleanic and curcanoleic acids (the latter belongs to the same group as ricinoleic and crotonic acids) (Watt and Breyer-Brandwijk, 1962). In the Indian plant, vitexin and isovitexin (flavonoids) were found (Sankara, 1971). The seeds contain a mucilage and a toxalbumin, curcin, with seven protein groups (Mourgue et al., 1961; Hufford and Oguntimein, 1978). In the fruit, roots and bark, cyanic acid, and in the bark a steroid saponoside have been found (Watt and Breyer-Brandwijk, 1962).

P Molluscicidal activity against Bulinus globulus was shown by all Jatropha spp. tested. The methanolic extract of the fruit of J. gossypiifolia was the most potent. Its mean lethal concentration (LC50) was 11.55-16.24 p.p.m. The LC50 of the seed and that of the rootbark of J. curcas were 120.55 and 125 p.p.m., respectively, and the LC50 of the seeds and that of the stem of J. podagrica were 130.73 and 125.08 p.p.m., respectively. Thus these were ten times less potent than the extract of J. gossypiifolia. The potency remained stable after UV radiation and over a wide range of pH values, but was reduced in the presence of minerals and faecal impurities (Adewunini and Marquis, 1980). The molluscicidal properties of Jatropha were also examined by Amin et al. (1972) and the antibacterial and pharmacological properties of J. podagrica were studied by Odebiji (1980), Ojewole and Odebiji (1980) and Ojewole (1981).

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